1. Field of the Invention
The invention relates generally to the field of computer networking devices. More particularly, the invention relates to a message exchange protocol for interconnecting packet forwarding devices through an intermediate network interconnect device.
2. Description of the Related Art
Local Area Network (LAN) switches are typically employed to solve congestion problems associated with LANs that arise as workgroups and networks, such as an Ethernet, grow. (The terms Ethernet LAN, or simply Ethernet, Fast Ethernet LAN, or simply Fast Ethernet, Gigabit Ethernet LAN, or simply Gigabit Ethernet, as used herein shall apply to LANs employing Carrier Sense, Multiple Access with Collision Detection (CSMA/CD) as the medium access method, generally operating at a signaling rate of 10 Mb/s, 100 Mb/s, and 1,000 Mb/s, respectively over various media types and transmitting Ethernet formatted or Institute of Electrical and Electronic Engineers (IEEE) standard 802.3 formatted data packets). Switches reduce congestion, for example, by segmenting workgroups into different LANs having separate collision domains and switching traffic, i.e., data packets, between the workgroups at very high speeds.
Switches are generally offered as part of either a pure stackable or pure chassis-based product line thereby forcing network managers to choose between stackable or chassis switching. There are advantages to both approaches. For instance, stackable switches offer flexibility and low entry-cost, while chassis-based switches offer fault tolerance and high port-density.
What is needed is a combination of stackable and chassis switching technology, which will provide network managers an incremental way to build faster, more manageable networks. Additionally, as intranet requirements grow throughout an enterprise, it is desirable to have available a cost-effective migration path that allows the port density, fault tolerance and performance of LAN switches to scale dramatically. More particularly what is needed are packet forwarding devices, e.g. switches, and network interconnect devices (which may serve individually or coupled in parallel as an external backplane, for example) that are designed to bring together the flexibility and low entry-cost of a stackable system and the fault tolerance and high port-density of a chassis-based system. Further, it would be advantageous to provide a communication mechanism, such as a handshaking protocol or the like, to reduce the need for packet buffering and to simplify packet forwarding logic within the network interconnect device, thereby allowing such a network interconnect device to be manufactured at a reasonable cost.